共查询到14条相似文献,搜索用时 250 毫秒
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采用AA5052铝合金挤压管作内层基管、Q235碳素结构钢卷焊管作外层覆管的钢铝复合管对复合管颗粒介质胀形行为进行研究。通过塑性理论分析胀形过程中管间切向摩擦力及法向压力对基管应力大小的影响;利用数值模拟分析管间摩擦因数和覆管各向异性对基管的应变成形极限的综合影响,并给出单管、复合管胀形时的壁厚减薄情况和基管的应力、应变分布;通过管材颗粒介质内高压胀形试验,对比单管和复合管胀形条件下铝合金管的极限胀形比,分析复合管的变形协调性。结果表明:通过施加Q235碳素结构钢覆管,减小了AA5052基管胀形区中间截面处的双向拉应力,基管胀形区壁厚减薄变小,胀形比提高了22%,复合管下基管最大减薄率为17.5 %,成形性能显著提高。 相似文献
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为解决AA6061挤压管材成形性能极差的问题,建立了“固溶水淬+颗粒介质胀形+人工时效”的铝合金管件成形工艺流程。研究了固溶水淬和人工时效工艺参数对材料性能影响规律,并建立了考虑厚向应力的三维成形极限应力图;建立了管件颗粒介质胀形有限元仿真模型,分析管件变形特征质点的运动轨迹和应力应变状态,并应用理论成形极限图对管件破裂失稳点和胀形极限进行分析和预判。四方截面管件胀形工艺试验结果表明,颗粒介质胀形工艺与合适的热处理工艺相结合能够有效地解决AA6061挤压管材的成形问题;考虑厚向应力的三维成形极限应力图可作为铝合金管件胀形工艺方案制定的破裂失稳判据。 相似文献
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离散体颗粒介质使颗粒介质内高压成形工艺中的传压具有非均匀性、颗粒介质与管件之间摩擦作用显著等特征,基于此,建立了颗粒介质非均匀载荷传压模型,对凸环管件胀形工艺过程进行了理论推导和数值解析,探讨了内压状况和摩擦条件对管件成形性能的影响,并通过工艺试验对理论分析结果进行了验证。分析结果表明,颗粒介质内高压成形工艺所具有的内压非均匀性、介质与管坯摩擦作用显著两大特征可有效减小胀形过程中的壁厚减薄和成形压力。对比试验与理论分析结果表明,壁厚分布和成形压力的理论计算结果与试验结果一致,颗粒介质非均匀载荷传压模型的构建策略可用于管件成形的预测和分析。 相似文献
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AA6061铝合金挤压管材在常温下强度高但塑性差,难以成形复杂形状零件。基于此,提出了固溶处理+固体颗粒介质胀形+人工时效的工艺流程,通过固溶、淬火和时效等热处理工艺调整铝合金变形前后的力学性能,应用固体颗粒介质胀形技术实现管件塑性成形。以AA6061挤压铝合金管为研究对象,分析了固溶处理工艺参数对合金力学性能的影响,发现管材经固溶温度560℃且保温120min处理后,其延伸率提高3倍以上,强度和硬度也大幅降低,使合金管材的成形性能指标显著提高,具备了固体颗粒介质胀形管件的条件;对合金固溶处理后再人工时效处理的试验研究表明,人工时效温度180℃且保温360min时合金塑性下降,强度和硬度等性能指标均可恢复至初始状态。基于铝合金热处理工艺特征的研究,采用固溶处理+固体颗粒介质胀形+时效处理的工艺流程,成功试制了AA6061铝合金典型的正方形截面管件,其环向最大展长率可达34%。 相似文献
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在以聚氨酯橡胶为胀形介质的复合胀形三通管的工艺中,模具结构和加载路径是影响三通管件成形质量的重要因素,提出并采用斜面冲头和位移控制冲头折线加载的方法,在非线性显式动力分析软件ANSYS/LS-DYNA为数值模拟平台的基础上,建立了三通管复合胀形的有限元模型。通过对比研究斜面冲头与普通冲头,冲头折线加载与线性加载时对三通管件成形质量的影响。研究结果表明,随着斜冲头的斜度的增加,管件壁厚减薄率是先减小后增大,增厚率则是逐渐减小,优化冲头的斜度和采用轴向冲头与反压冲头折线加载可以有效的提高三通管件的成形质量。 相似文献
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介绍了一种用于液胀成形双金属复合管的模具。该装置具有自动适应内衬管和基管轴向长度变化量不等的特点,并能随着胀形力的变化与其轴向力自动可靠平衡,克服了成形设备的平衡力不稳定和控制复杂、易造成复合钢管质量不稳定的缺点,并能满足成形过程中由于超高压力产生的直径方向大变形量的可靠密封,使复合管内衬管在超高压液体的作用下与基管紧密结合,具有结构简单、控制方便、可靠性高、成本低等优点。 相似文献
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S. M. H. Seyedkashi H. Moslemi Naeini Y. H. Moon 《Journal of Mechanical Science and Technology》2014,28(7):2845-2852
Feasibility study has been performed to estimate the optimized process conditions in warm tube hydroforming based on the simulated annealing optimization method. Precise prediction and control of process parameters play an important role in forming at warm conditions. Optimal pressure and feed loading paths are obtained for aluminium AA6061 tubes through the simulated annealing algorithm in conjunction with finite element simulations. Numerous axisymmetric geometries are investigated and the effects of expansion ratio, corner fillet to thickness ratio, and initial diameter to thickness ratio are studied. For the feasibility estimation, warm hydroforming experiments have been conducted on aluminum AA6061 under optimal designed conditions. The results show that the optimization procedure used in this research is a reliable and feasible tool in determination of optimal process conditions for the sound warm hydroforming process. 相似文献
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The present paper investigates the axial splitting and curling behaviour of circular metal tubes. Mild steel and aluminum circular tubes were pressed axially onto a series of conical dies each with different semi-angle. By pre-cutting eight 5 mm slits which were distributed evenly at the lower end of each tube, the tube split axially and the strips curled outward. Experiments showed that this mechanism results in a long stroke and a steady load. An approximate analysis is presented which successfully predicts the number of propagated cracks, the curling radius and the force applied. This analysis takes into account ductile tearing of the cracks, plastic bending/stretching and friction. Effects of tube dimensions, semi-angle of the die and friction are discussed in detail. 相似文献
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Yuung Ming Huang 《The International Journal of Advanced Manufacturing Technology》2009,43(11-12):1167-1176
An elasto-plastic incremental finite element computer code based on an updated Lagrangian formulation was developed to simulate the flaring and nosing processes of a metal tube in the asisymmetric condition. The extended r min technique was used to treat the elastic–plastic stress state and to solve contact problems at the tool–metal interface. A modified Coulomb’s friction law was introduced to treat the alternation of the sliding–sticking state of friction at the contact interface. The forming performed analysis using the finite element method and experiment. To examine the influence of the thickness ratio and the optimum punch semi-angle and friction on the forming load of the two-ply metal tubes consisting of soft aluminum, hard aluminum, and copper. The calculated tube geometries and the relationship between punch load and stroke are in good agreement with the experimental data. 相似文献
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A. Fatemi M. R. Morovvati F. R. Biglari 《The International Journal of Advanced Manufacturing Technology》2013,68(1-4):263-276
In this paper, the influence of tube material, microstructure, and heat treatment on process responses of tube hydroforming has been studied. One of the most important parameters in performing a successful tube hydroforming process is the selection of appropriate material for tubes. In the analysis section, effective parameters for the selection of an appropriate tube material for the hydroforming process have been investigated; it was concluded that higher strain hardening exponent (n), elasticity modulus (E), and anisotropy index (R) can enhance formability in this process; and the effects of microstructure and heat treatment on the formability of ASTM C11000 copper and ASTM AA1050 aluminum have been investigated. Consequently, four different heat treatment processes, which had different heating temperatures and durations, were selected, in addition to different cooling methods for each of the materials. In the experimental tests, the effects of these heat treatment methods on maximum bulging height, thickness strains, and final forming pressures were scrutinized. The effects of heat treatment on copper microstructure were also studied through metallographic tests; on the other hand, the effects of microstructure on tube hydroforming process were justified. As a result of these analyses, two heat treatment methods, namely, heating to 450 and 350 °C for 15 min and cooling in water, were recommended for copper and aluminum, respectively. Using these methods and due to their consequent fine and homogenous microstructure, higher mechanical strength and increase in material formability was achieved by attaining higher thickness strain and bulging height values. Finally, after extracting the mechanical properties of the two materials and comparing them with each other, parameters of strength coefficient and strain hardening exponent were reported as two effective factors that would improve tube deformation by tube hydroforming process. 相似文献